A standard shipping pallet comprises a plurality of coplanar boards secured to the upper edges of a plurality of transverse stiffening ribs. Normally three stiffening ribs are provided to form two openings extending parallel to the stiffening ribs for the tines of a fork lift. In order that the fork lift can also operate transversely it is also standard practice to form these stiffening ribs with three equispaced downwardly projecting feet forming two further openings or passages extending transversely to the stiffening ribs and parallel to the boards secured to their upper surfaces. It is also standard practice to nail further boards across these feet on the lower surface parallel to the upper boards so that the pallet is quite strong and can stand on relatively uneven ground. Rather than using a plurality of parallel coplanar boards on the top and bottom it is also, of course, possible to use a single very wide board or piece of plywood.
It is known to form such a stiffening rib of particles, for instance by a method such as described in my copending application Ser. No. 176,004 filed Aug. 17, 1980. This application describes a method of and apparatus for the cold extrusion of a mixture of plant particles and a binder, especially for the production of load-bearing beams and similarly shaped bodies in which the plant particles are wood chips or the like. A plunger ram displaces the mixture piston-fashion into the extrusion passages in which hardening can occur under conditions such that the material flows during compaction and is compressed with a densification ratio of 2:1 to 4:1. The resultant beam is relatively strong, inexpensive to manufacture, and has excellent dimensional stability.
The main problem with a pallet so constructed, which is described in German patent publication No. 2,508,493 filed Feb. 27, 1975 by H. Lewin, is that the stiffening ribs when bent frequently fracture adjacent the feet, that is at the corner between the upright portion of the side of the foot and horizontal portion of the stiffening ribs between the feet. Fracture at this point is particularly disadvantageous because it lies between the upper and lower boards and, therefore, allows the pallet to come apart.